X-ray attenuation in lead, aluminum, and concrete in the range 275 to 525 kilovolts

A great deal of work has been done in recent years to determine how the attenuation of an x-ray beam is modified by the contribution of radiation scattered in the absorber. This scattering contribution depends on the irradiated area and on the solid angle subtended by the detector at the absorbers. The limiting case of a small irradiated area and a small detector solid angle is referred to as “good” or “narrow-beam” geometry; “poor” or “broad-beam” geometry implies that the irradiated area or the detector solid angle is large. In protection studies the term “broad beam” is slightly more restrictive, being used when both the irradiated area and the detector solid angle are large enough so that any further increase in either would not affect the attenuation. It has been found that when the Compton effect contributes to the absorption mechanism, the attenuation per unit thickness under broad-beam conditions is less than with a narrow beam. This increase in penetration is due to the fact that the Compton effe...